Humans have pumped so much groundwater that the Earth's axis has shifted, says a study

A new study has found that human-made groundwater is affecting the Earth’s tilt as more liquid is released from underground reservoirs.

Groundwater provides drinking water for people and livestock, and helps in irrigating crops when there is no rain. However, the new study shows that more than a decade of groundwater extraction has shifted the planet’s spin axis, moving it eastward at a rate of 1.7 inches (4.3 centimeters) per year.

That change can be seen on Earth’s surface as well, researchers report in the June 15 issue of the journal. Geophysical Research Letters.

“The Earth’s spin pole will actually change a lot,” lead researcher Ki-wen Seo, a professor in the Department of Earth Sciences at Seoul National University in South Korea, said in a news release. “Our study shows that the redistribution of groundwater between climate-related factors actually has a significant impact on the polar opposite.”

Earth’s sliding axis

You may not feel the rotation of the Earth, but it is spinning on its north-south axis at 1,000 miles per hour (1,609 kilometers per hour).

Surendra Adhikari, a research scientist at NASA’s Jet Propulsion Laboratory, said the seasonal change is linked to the angle of the planet’s spin axis, and that axis wandering over geologic time can affect climate globally. . Adhikari was not involved in the study.

Earth’s interior is a dense hot core covered with rock and magma. But there is also a lot of water in the very rocky layer. Beneath the planet’s surface, rocky reservoirs known as aquifers are estimated to hold 1,000 times more water.

Over geologic time, the wandering axis could affect Earth’s climate on a global scale, scientists say. – NASA/File

Between 1993 and 2010, According to the study, humans withdrew more than 2,150 gigatons of groundwater from the earth, mostly in western North America and northwestern India, by 2015. Estimates published in 2010. It would raise global sea level by 0.24 inches (6 millimeters).

In the year In 2016, another group of researchers They found that between 2003 and 2015, the slip in the Earth’s rotation axis may be related to the number of glaciers and ice sheets, as well as the planet’s terrestrial liquid water.

In fact, any change in mass on Earth, including atmospheric pressure, can affect the spin axis, Seo told CNN in an email.

But the axis shifts caused by changes in atmospheric pressure are periodic, meaning the axis of rotation wanders and then returns to its original position, Seo explained. Seo and his colleagues had questions about the long-term changes in the axis — particularly how groundwater contributed to that phenomenon. It was not calculated in previous studies.

It shows the effect of groundwater extraction

The Earth’s axial shift is indirectly measured by radio telescopes using stationary objects in space – quasars – as fixed reference points. For the new study, scientists took data on groundwater discharge in 2010 and incorporated it into computer models, along with observational data about ice loss and sea-level rise, and predictions about polar shifts.

The researchers evaluated sea-level variations using changes in the mass of groundwater in the model to determine how much of the axis shift was caused by groundwater withdrawal alone, Seo said.

The redistribution of groundwater tilted the Earth’s axis of rotation to the east more than 31 inches (78.7 centimeters), according to the models, in less than two decades. The most prominent driver of long-term variations in the axis of rotation was already known to be mantle flow – the movement of molten rock between the Earth’s crust and outer core. The new modeling shows that groundwater extraction is the second largest area, Seo said.

“This is a great contribution and an important document,” Adhikari said. “They considered the role of groundwater absorption in polar movement, and it’s very important.”

Future models could use observations of Earth’s rotation to illuminate the past, Seo added. “The information is available since the end of the 19th century,” he said. With this information, scientists can track changes in the planetary system by looking back as the climate warmed over the past 100 years.

Groundwater drainage can be a lifeline, especially in parts of the world affected by drought due to climate change. But underground storage liquid water is limited; Once spilled, they are slow to refill.

And groundwater extraction doesn’t just destroy valuable resources; The new findings show that this movement has an unwanted global effect.

“We have affected the Earth’s systems in different ways,” said Seo. “People need to know this.”

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